ObjectivesTo clarify the association between glucose intolerance and high altitudes (2900–4800 m) in a hypoxic environment in Tibetan highlanders and to verify the hypothesis that high altitude dwelling increases vulnerability to diabetes mellitus (DM) accelerated by lifestyle change or ageing.DesignCross-sectional epidemiological study on Tibetan highlanders.ParticipantsWe enrolled 1258 participants aged 40–87 years. The rural population comprised farmers in Domkhar (altitude 2900–3800 m) and nomads in Haiyan (3000–3100 m), Ryuho (4400 m) and Changthang (4300–4800 m). Urban area participants were from Leh (3300 m) and Jiegu (3700 m).Main outcome measureParticipants were classified into six glucose tolerance-based groups: DM, intermediate hyperglycaemia (IHG), normoglycaemia (NG), fasting DM, fasting IHG and fasting NG. Prevalence of glucose intolerance was compared in farmers, nomads and urban dwellers. Effects of dwelling at high altitude or hypoxia on glucose intolerance were analysed with the confounding factors of age, sex, obesity, lipids, haemoglobin, hypertension and lifestyle, using multiple logistic regression.ResultsThe prevalence of DM (fasting DM)/IHG (fasting IHG) was 8.9% (6.5%)/25.1% (12.7%), respectively, in all participants. This prevalence was higher in urban dwellers (9.5% (7.1%)/28.5% (11.7%)) and in farmers (8.5% (6.1%)/28.5% (18.3%)) compared with nomads (8.2% (5.7%)/15.7% (9.7%)) (p=0.0140/0.0001). Dwelling at high altitude was significantly associated with fasting IHG+fasting DM/fasting DM (ORs for >4500 and 3500–4499 m were 3.59/4.36 and 2.07/1.76 vs <3500 m, respectively). After adjusting for lifestyle change, hypoxaemia and polycythaemia were closely associated with glucose intolerance.ConclusionsSocioeconomic factors, hypoxaemia and the effects of altitudes >3500 m play a major role in the high prevalence of glucose intolerance in highlanders. Tibetan highlanders may be vulnerable to glucose intolerance, with polycythaemia as a sign of poor hypoxic adaptation, accelerated by lifestyle change and ageing.

events that can be prevented at a population level through smoking cessation is substantial. 2 It is likely that selective attrition due to greater mortality in smokers explains, in part, the observed low prevalence of smoking, but with improved medical care, this survival difference may be decreasing; this sample experienced a change in demographics over time, with an increasing proportion of men in later surveys. Other factors that probably contributed to the low prevalence of smoking include implemented population-level interventions, such as legislation limiting smoking in public places and antismoking programs (e.g., ClearWay Minnesota).Limitations of the present study are the restriction to community-dwelling individuals, a possible underrepresentation of smokers due to volunteer bias, recall bias, decreasing response rate, modest sample size, and unclear generalizability to other geographic areas.In conclusion, between 1990 and 2009, the prevalence of current smoking in older adults remained consistently low as a result of quitting, antismoking programs, and probable effects of selective mortality in smokers. With an aging population, the absolute number of elderly smokers will probably increase despite its low prevalence. ACKNOWLEDGMENTSConflict of Interest: The editor in chief has reviewed the conflict of interest checklist provided by the authors and has determined that the authors have no financial or any other kind of personal conflicts with this paper. *P < .05, † P < .01, ‡ P < .001; normocythemia versus polycythemia; chisquare test, Student t-test, logistic regression. § Adjusted for age, sex, obesity, hypoxia, race, and residence altitude using multiple logistic regression. SD = standard deviation; SpO 2 = oxygen saturation; BMI = body mass index; DM = diabetes mellitus; IFG = impaired fasting glucose.

Milk protein polymorphisms in yaks, cattle and their hybrids were examined in the yaks and cattle as was found in the Khumbu district in the previous study. Traditional breeding by Sherpa may have discriminated among types of animals properly and their mating program seems to have been managed under a strict rule on the hybrid production.

No abstract

No abstract